1. Field
The present inventive concept relates to a speaker. More particularly, the present inventive concept relates to a structure supporting a voice coil of a slim-type speaker.
2. Description of the Related Art
A speaker is an electro acoustic transducer and generally has a supporting structure which supports the linear reciprocating motion of a voice coil. The supporting structure is disposed in order for the voice coil to maintain linearity at a center thereof while the voice coil performs linear reciprocating motion or piston motion. The supporting structure may include dampers (or spiders), edges (or surrounds), etc.
The slim-type speaker is a speaker of a shape having a cross-section of which the width is smaller than the length, and may be designed to have a diaphragm of an elongated circular shape, an ellipse shape or a rectangular shape, but not a circular shape. If the diaphragm of the speaker is in the form of an elongated circular shape, an ellipse shape or a rectangular shape, there is a limitation as to the area and/or shape of a damper that connects to a bobbin of the voice coil and connects to a frame of the speaker, and maintains position in the center of the voice coil.
FIGS. 1 and 2 illustrate related art slim-type speakers. FIG. 1 is a sectional view schematically illustrating a slim-type speaker of related art. FIG. 2 is a plan view illustrating the slim-type speaker of FIG. 1, after removing a diaphragm.
Referring to FIGS. 1 and 2, a damper 101 is formed with a horizontally long shape and is fixed in order to connect a portion of a bobbin 105 of a voice coil 103 and a frame 110. As illustrated in FIGS. 1 and 2, bobbin 105 is stably supported in a long-axis direction (an X direction) of the speaker 100 by a long-axis damper 101 disposed in a horizontal direction. However, since damper 101 cannot be disposed in a short-axis direction (a Y direction) of speaker 100, namely, in a vertical direction, bobbin 105 is supported in the short-axis direction of the speaker 100 by dampers 107 disposed in the horizontal direction. Therefore, bobbin 105 is supported less stably in the short-axis direction than in the long-axis direction of speaker 100. Although not illustrated, if no damper is disposed for supporting bobbin 105 in the short-axis direction of speaker 100, the support of bobbin 105 becomes more unstable.
The supporting method as described above makes it difficult to support bobbin 105, around which voice coil 103 is wound, by the same supporting force with respect to a center point thereof. If the supporting force of bobbin 105 is not uniform, when voice coil 103 reciprocates in a vertical direction, different size forces may be applied to portions of dampers 101 and 107 which are adhered to bobbin 105 of voice coil 103. This results in voice coil 103 generating wobble, resulting in an increase in distortion near a resonance frequency having relatively broad amplitude.
In other words, if dampers 101 and 107 are designed to have an asymmetrical shape with respect to the center of speaker 100, nonlinear motion of voice coil 103 may occur. If voice coil 103 moves nonlinearly, wobble and/or distortion in sound produced by speaker 100 may be increased.
Therefore, proper operation of a slim-type speaker 100 requires dampers formed symmetrically with respect to the center of speaker 100.